At an election later that year, the CLP performed better than expected, bringing the party to the brink of power when, in 2009, Alison Anderson resigned from the Labor government and Independent MLA Gerry Wood became the kingmaker.

Mr Mills maintained the party's momentum through to the 2012 election when he became chief minister.

Opposition Leader Delia Lawrie told parliament Mr Mills would be remembered for his decency and ability to forge relationships.

"You, as best as possible, shied away from playing the person," she said.

"You were often put in position where you might have but your core decency led you to ... land in a better and more gentlemanly space."

Country Liberals likely to hold seat

A by-election for the seat of Blain will be held within the next 20 days.

Policeman and former candidate Geoff Bahnert is tipped to run for Labor.

But political commentator and former Labor MLA Ken Parish, a law lecturer at Charles Darwin University, says the Country Liberals are likely retain the seat.

"[The CLP has] a 13 per cent margin," he said.

"Even if you make a generous allowance for the loss of incumbency and even if you assume there is still some degree of unpopularity with the CLP government from earlier decisions on water rates and increases in power charges and so on, I would expect the CLP will hold on to the seat fairly comfortable."